๐ ็ธฝ็ฎ้ ๏ฝ ๐ ่ฑๆๅๆ๏ผๆฌ็ฏ๏ผ ๏ฝ ๐ ๅฎๆด็ฟป่ญฏ ๏ฝ โญ ็ฒพ่ฏ็ญ่จ
INTRODUCTION
As a major barrier against the external environment, one of the skinโs major functions is defense against potential insults by microbial, chemical, and physical agents. Over the past several decades, it has become clear that the skin is not a mere passive mechanical barrier to the outside world but rather represents an active member of the bodyโs immune system. As such, the skin is inhabited by a myriad of resident immune cells, which, together with recruited inflammatory and adaptive immune cells, protect the individual from external and internal danger signals. Accordingly, the term โskin-associated lymphoid tissuesโ (SALT) has been coined to reflect the importance of the cutaneous immune response in tissue homeostasis and repair.
The classical immune response, also referred to as the adaptive immune response, is characterized by specificity that is due to immunologic memory (specific immunity). Innate immunity is a more primitive defense system that acts in a rapid but less specific manner. Both types of responses can be generated in the skin. Adaptive immune responses in the skin, however, are not always protective but can also be harmful in nature, e.g. allergic or autoimmune reactions. Numerous skin diseases are caused by T lymphocytes and/or autoantibodies and are therefore immunologically mediated. Consequently, many dermatoses respond favorably to immunosuppressive therapy administered either systemically or topically.